(1) Field of the Invention
The inventive subject matter of the application pertains to a manually operated reciprocating liquid pump that employs both a priming valve and a check valve, where the priming valve performs the dual functions of priming the pump and sealing the pump to prevent inadvertent leakage of liquid through the pump when it is not in an upright orientation.
(2) Description of the Related Art
Manually operated reciprocating liquid pumps of the type employing a plunger with a dispensing head that is manually reciprocated downwardly into a pump housing connected to a liquid container and is then spring biased upwardly out of the pump housing to draw liquid out of the container and dispense the liquid often employ both a priming valve and a check valve. The priming valve unseats on the downward movement of the plunger into the pump housing to allow air in the empty pump housing to escape through the plunger and dispensing head, and then seats on the return stroke of the plunger upwardly out of the pump housing to draw liquid in the container up into the pump housing. The check valve seats on the downward movement of the plunger to prevent air or any liquid contained in the pump housing from being forced back into the container, and then unseats on the upward movement of the plunger to allow the vacuum created in the pump housing by the plunger's upward movement to draw liquid from the container past the check valve into the pump housing.
Very often ball valves are used for both the priming valve and check valve in manually reciprocated liquid pumps. However, the functioning of ball valves is dependent on gravitational forces which direct the ball of the valve downwardly to its seated position. Should a liquid container having a reciprocating pump with ball valves be moved from its upright orientation, for example being knocked over on its side or positioned in an inverted orientation while packaged during shipment, gravity no longer seats the ball valves and the liquid in the container can pass through and leak from the pump.
Reciprocating plunger pumps have been designed in a variety of constructions to prevent the pumps from leaking when the liquid container to which they are attached is positioned on its side or inverted. However, many of these designs require an elaborate construction of the reciprocating plunger pump to prevent its leaking and often require additional component parts to be added to the pump which increase its cost of production.